Interestingly, the whole dispute about whether to have six or two candles
@bbbbbbb aludes to is kind of a non-issue, because even in the Roman Rite, low masses traditionally had only two candles lit. In addition, there would be a seventh candle lit if any presanctified hosts were in the tabernacle. This is interesting because in the Orthodox churches we see a minimum of two lights on the holy table, sometimes three, and as many as seven in the case of some Eastern Orthodox churches, where one finds a seven-branched oil lamp, which is also interesting in that Vespers in the Eastern rites consists of, among other things, seven lamp lighting prayers, except in Lent on those days when it is served as part of the Presanctified Liturgy of St. Gregory, when there are only four lamplighting prayers; in addition the consecration of Holy Oil in the Coptic and Byzantine Rites consists of a set of seven sets of scripture lessons and prayers as seven oil lamps or wicks into a bowl containing, in either case, the oil to be consecrated, are lit.
However, another interesting fact is that the Coptic church uses paraffin candles on its altars, whereas the Eastern Orthodox use oil lamps, and only pure beeswax candles, but only outside the altar, away from the iconostasis, past which no animal products are allowed.
The lights on some altars in newer parishes of the Assyrian Church of the East are electric, interestingly enough.
In general, it can be said that all Christian denominations agree that at least two lights are required on the altar, but whether or not to use more, in the case of some churches such as the Anglicans, comes down to a question of aesthetics.